This invention relates to a method for cooling a compressed air and an apparatus thereof which is preferably used at the time when a large amount of high-temperature compressed air generated by an air compressor of a manufacturing factory or the like, for example, is fed to an air dryer, wherein a dried compressed-air having a low temperature obtained by effectively using warm air and cool air generated in a vortex tube and without using any refrigeration type air dryer is fed to the air dryer and after a favorable gas-liquid separation is achieved by the air dryer, the compressed air is fed to an air tool so that a possible occurrence of failure and functional reduction of the air tool can be prevented.
The compressed air ejected from an air compressor contains water and oil content mixed with each other. When this compressed air is fed to an air tool such as an air dryer, impact wrench, painting gun or the like, the inside of the air conduit is rusted or the component elements of the air tool are rusted, thereby causing the functional reduction and failure of the tool. In view of the above-mentioned problems, the outlet duct for the compressed air is provided with an air dryer as a gas-liquid separator so that the compressed air is separated into gas and liquid by the air dryer and the dried compressed air is fed to the air tool.
The air dryer is provided, for example, with an upper cover attached to the upper part of the hollow cylindrical body and communicated with the inside, a conduit forming a duct for the compressed air is screwed into the inlet passage and outlet passage which are formed in the both sides of the cover, a hollow cylindrical partition tube is disposed inside the hollow cylindrical body, and a plurality of partition members as a gas-liquid separation member are superimposed within the partition tube such that one partition member is placed on another.
Then, the compressed air introduced into the hollow cylindrical body from the inlet passage is guided to the lower side of the partition members and ejected from the through-hole, the condensed moisture owing to adiabatic expansion is discharged from a drain hole (not shown) formed in the lower end part of the hollow cylindrical body, and the moisture-removed dry air is discharged from the outlet passage and fed to the air tool side (for example, see Japanese Patent No. 4789963).
However, since the air dryer is inserted into the ejection duct for the compressed air and used in that condition and the ejection duct is installed in the indoor of the factory or the like, there are such problems that the installation space and the area where the air dryer is used are limited.
Moreover, it gives arise to additional such problems that even in the case where the air dryer is arranged on the upstream or intermediate-stream side of the ejection duct and the compressed air is separated into gas and liquid by the air dryer, the moisture is condensed again depending on the neighboring temperatures and mixed with the compressed air, and thus, the original gas-liquid separation state is decreased and the compressed air with the moisture mixed therewith is fed to the air tool, thus resulting in failure of the air tool and/or a situation where the air tool becomes unable to use. In the case where the air tool is a painting gun, it becomes unable to perform the predetermined painting and therefore, the painting gun becomes unable to use. Therefore, in order to separate the compressed air into gas and liquid effectively and accurately by using the air dryer, it is preferable that the cooled and dried compressed-air is fed to the air dryer.
In order to remove the above-mentioned problems, one attempt is made wherein, for example, the compressed air of the air compressor is fed to a refrigeration type air dryer. This refrigeration type air dryer is constructed such that a refrigerating circuit comprising a compressor, a condenser and a cooling device is installed inside an air dryer body, and the compressed air is fed into the cooling chamber where the compressed air is cooled and dried (for example, see Japanese Patent Application Laid-Open No. 1998-235132 and Japanese Patent No. 3020151).
However, since the refrigeration type air dryer is expensive and requires a high installation cost and in addition, the refrigeration type air dryer is always driven at the time when the air tool is in use, it gives rise to such a problem that the operating cost becomes enormous.
In order to solve the above-mentioned problem, an air dryer is known, wherein a first and second heat exchanger forming a refrigeration circuit are arranged inside the air dryer, a coolant is fed to those heat exchangers, the cooling water introduced to the first heat exchanger is cooled and introduced to the second heat exchanger, compressed air is introduced to the second heat exchanger and the compressed air is cooled by the cooling water (for example, see Japanese Patent Application Laid-Open No. 1999-19461).
However, it gives rise to such a problem, among others, that since this air dryer is required to cool the cooling water, a refrigeration circuit including a first and second heat exchanger is required and the equipment cost and operational cost become enormous.
Another type of equipment is also known as another means for water cooing the compressed air, in which a compressed air tube for introducing compressed air of an air compressor is arranged in a cooling water tub, a water cooling type aftercooler is disposed at a bottom part of the cooling water tub, the compressed air is introduced to the aftercooler and cooled, the cooled compressed air is a refrigeration type air dryer, and the compressed air is further cooled (for example, see Japanese Patent Application Laid-Open No. 1999-193782).
However, this equipment has such a problem that since a refrigeration type air dryer is required in addition to the water cooling type aftercooler, the installation cost becomes enormous, long time is required for cooling the compressed air, and operational cost thereof is increased.
In order to solve the above problem, another prior art is known as an apparatus and method for generating a dried air to be used for cleaning a substrate, such as a semiconductor wafer, which comprises a compressed air generator for generating a compressed air, a vortex tube for generating a cold air and warm air by the generated compressed air, a vessel connected to the vortex tube and receiving the cold air sent from the vortex tube, and a heater for heating the cold air received in the vessel, and in which the heater is connected to the vortex tube, the cold air received in the vessel is heated to a normal temperature using the warm air sent from the vortex tube, and the normal temperature air is introduced to a substrate processing chamber (for example, see Japanese Patent Application Laid-Open No. 2007-175643).
However, it gives rise to such a problem that although the vortex tube can easily obtain cold air, it is expensive and since the amount of air ejected from the vortex tube is generally small, it is unable to meet the manufacturing factory where a large amount of compressed air is used. Moreover, the vortex tube has such additional problem that since it is necessary to operate continuously the compressor in order to obtain the cold air, electricity charges become enormous.
Moreover, since the cold air side connection tube and the warm air side connection tube for connecting the vortex tube and the buffer are exposed inside the dry air generator, it gives rise to such a problem that because of the poor thermal efficiency in the buffer, a stable compressed air having a normal temperature is difficult to obtain, and in addition, in spite of the fact that the connection tube on the warm air side is decreased in temperature and the temperature of the warm air gradually approaches the dew point, the warm air now having a decreased temperature is directly brought to the buffer, thereby making it difficult to obtain a sufficiently dried dry air.